Hi Stephan. Here some website address from companies in Doha. Have a look at it, you probably find something suitable.

Dolphin Energy
Recruitment Office - Qatar : +974 413-8755
e-mail : [email protected]
www.dolphinenergy.com

QChem (Qatar Chemical Company Ltd.)
First Floor, Salam Tower, Al-Corniche Street
PO BOX 24646 Doha - Qatar Tel +974 - 4847111
www.qchemp.com.qa

Occidental Petroleum of Qatar, Ltd.
www.oxy.com

Qatar Petroleum
www.qp.com.qa

This one is not perticularly in Qatar, but sometimes you will find a vacancy based in Qatar: